System and method for the recovery of oil in water emulsion spilled in water

ABSTRACT

A method for on line recovery of oil from an oil in water emulsion spilled in water includes the steps of: obtaining a stream of recovered material including an oil in water emulsion and water; injecting a gas into the stream and applying shear so as to provide an injected mixture wherein oil from the oil in water emulsion is adhered to bubbles of the gas; passing the injected mixture to a flotation compartment for allowing the oil adhered to the bubbles to rise to a surface of the injected mixture; and removing the oil from the surface of the injected mixture.

BACKGROUND OF THE INVENTION

The invention relates to a system and method for recovery and separationof an oil in water emulsion spilled in water.

It is widely recognized that spills of oil and fuel such as oil in wateremulsions and the like pose a serious ecological or environmental threatwhich must be addressed. These problems are exacerbated with oil inwater emulsions due to interaction between the emulsion and water whichrenders recovery more difficult. Methods have been proposed forrecovering oil from spills and the like. However, the need remains for asystem and method for oil recovery, especially recovery from a spill ofan oil in water emulsion, which effectively recovers a large percentageof the spilled oil.

It is therefore the primary object of the present invention to provide asystem and method for recovery of spilled oil which is effective inrecovering oil in the form of an oil in water emulsion.

It is a further object of the present invention to provide a system andmethod for recovery wherein a large percentage of spilled oil isrecovered.

It is a still further object of the present invention to provide asystem and method for recovery which functions in an on line continuousmanner to rapidly contain and address a potentially hazardous spill.

It is another object of the present invention to provide a system andmethod for recovery of a spilled oil in water emulsion which providessubstantially separated oil and substantially oil free water.

Other objects and advantages of the present invention will appearhereinbelow.

SUMMARY OF THE INVENTION

In accordance with the present invention, the foregoing objects andadvantages are readily attained.

According to the invention, a method is provided for on line separationof oil from an oil in water emulsion spilled in water which comprisesthe steps of obtaining a stream of recovered material including an oilin water emulsion and water; injecting a gas into said stream andapplying shear so as to provide an injected mixture wherein oil fromsaid oil in water emulsion is adhered to bubbles of said gas; passingsaid injected mixture to flotation means for allowing said oil adheredto said bubbles to rise to a surface of said injected mixture; andremoving said oil from said surface of said injected mixture.

A system is also provided according to the invention for on linerecovery and separation of oil and an oil in water emulsion spilled inwater which comprises means for obtaining a stream of recovered materialincluding an oil in water emulsion and water; means for injecting a gasinto said stream and for applying shear so as to provide an injectedmixture wherein oil from said oil in water emulsion is adhered tobubbles of said gas; and means for allowing said oil adhered to saidbubbles to rise to a surface of said injected mixture whereby said oilcan be removed from said surface.

BRIEF DESCRIPTION OF THE DRAWING

A detailed description of preferred embodiments of the inventionfollows, with reference to the attached drawing which schematicallyillustrates a system in accordance with the present invention.

DETAILED DESCRIPTION

The invention relates to a system and method for on line separation ofoil from an oil in water emulsion spilled in water.

As set forth above, the recovery of oil, especially in the form of anoil in water emulsion spilled in bodies of water poses an ecological orenvironmental threat which must be addressed. The present inventionprovides a system and method whereby spilled oil, especially a spilledoil in water emulsion such as Orimulsion™, a product provided by BITOR,S. A., can be rapidly recovered from the water in which it is spilled,and further wherein the oil phase is readily separated therefrom.

Although a wide variety of oil or oil in water emulsions could suitablybe recovered in accordance with the system and method of the presentinvention, the present disclosure will be made in terms of recovery ofOrimulsion™, which is an emulsion of viscous bitumen in water, typicallyhaving a ratio of bitumen to water of approximately 70:30.

Referring to the attached drawing, a system 10 in accordance with thepresent invention is illustrated. According to the invention, system 10preferably includes a base 12 or other platform which can suitably bepositioned at the site of a spill, for example as a floating device orattachment to a water-going vessel and the like. According to theinvention, system 10 preferably includes a primary pump 14 having aliquid inlet 16 for obtaining the mixture of oil in water emulsion andenvironmental water from which the oil in water emulsion is to berecovered. As shown, system 10 is preferably positioned with liquidinlet 16 positioned to draw in a stream of recovered material includingthe oil in water emulsion and, inevitably, a portion of water which willbe referred to herein as environmental water.

In accordance with the invention, the stream of recovered material issubjected to the injection of air and shearing conditions so as todisperse bubbles of air or other suitable gas throughout the mixture,thereby encouraging the adhesion of oil in the oil in water emulsion andenvironmental water mixture to the air bubbles so formed. According tothe invention, and advantageously, oil is then readily separated fromthe water mixture constituting environmental water and water separatedfrom the oil in water emulsion in a relatively short flotation stepwherein oil adhered to air bubbles floats to the surface of therecovered product and is readily removed or skimmed therefrom.

Referring back to the FIGURE, an air inlet 18 is preferably provided andcommunicated with liquid inlet 16 so that a quantity of air as desiredcan be injected into the stream of liquid recovered through liquid inlet16. The air mixture drawn in from liquid inlet 16 and inlet 18 is thenintroduced to primary pump 14 wherein shear is applied so as to form thedesired air bubbles dispersed throughout the mixture, and encourageadhesion of oil to the air bubbles as desired. From primary pump 14, theair injected stream is preferably fed to a multi-compartment tank 20wherein bubble flotation and skimming so as to recover the oil phase areaccomplished. This mixture may suitably be fed to tank 20 through line22 as shown.

System 10 in accordance with a preferred embodiment of the presentinvention preferably also includes a recycling structure includingoutlet pipes 24, additional pumps 26, and return pipe 28 which areprovided for drawing liquid from tank 20 and subjecting same toadditional shearing in pumps 26. Furthermore, additional air inlets 30are preferably provided so that additional air can be injected to theliquid mixture upstream of additional pumps 26 as desired. In accordancewith the invention, air is preferably injected and shear is preferablyapplied so as to obtain an adhesion of oil to air bubbles of at leastabout 80% of the oil entering inlet 16, more preferably at least about90%, and ideally at least about 98%.

In accordance with the preferred embodiment as illustrated in thedrawing, air and shear may preferably be applied at primary pump 14 soas to provide adhesion to bubbles of at least about 80% of the oilentering inlet 16, and additional air and shear can be applied throughadditional pumps 26 and air inlets 30 so as to increase the adhesion ofoil to air bubbles to at least about 98%. A further additional air inlet32 may be positioned downstream of primary pump 14 if desired forinjection of still further air if needed.

System 10 also includes tank 20 as described above preferably havingthree compartments, specifically a receiving compartment 34, a flotationcompartment 36 and a separation compartment 38. Receiving compartment 34receives a stream of recovered material from line 22 and also fromreturn pipe 28 which is preferably provided at sufficient velocity as toassist in the application of shear and subsequent adhesion of oil to airbubbles. From receiving compartment 34, air injected liquid is passed toflotation compartment 36 wherein a relatively short residence timeprovides for significant flotation of oil adhered to air bubbles towardthe surface of liquid resident in flotation compartment 36. In order todampen or eliminate turbulence which could be caused by introduction ofliquid to receiving compartment 34, flotation compartment 36 preferablyis communicated with receiving compartment 34 through a divider 40having an upper cutout 42 and a lower cutout 44. Upper cutout 42 ispreferably provided so as to allow flow from receiving compartment 34 toflotation compartment 36 in a surface flow zone, while lower cutout 44is preferably provided so as allow flow from receiving compartment 34 toflotation compartment 36 in a bottom flow zone. In this way, turbulencewhich could inhibit flotation of oil toward the surface is avoided.

As set forth above, a relatively short residence time in flotationcompartment 36 results in significant separation of oil throughflotation to the surface. In accordance with the invention, and for atypical Orimulsion™ product, a residence time of about 1 minute to about11/2 minutes is sufficient to provide substantial separation.

From flotation compartment 36 the at least partially separated liquidincluding adhered oil and water are passed to separation compartment 38.In separation compartment 38, the remainder of oil, if any, which didnot rise to the surface in flotation compartment 36 is allowed tocomplete the flotation so as to provide a top layer 46 containing oilrecovered from the mixture.

Remaining water 48 in separation compartment 38 preferably has aresidual oil content of less than or equal to about 20 parts permillion, and is therefore suitable for return to the water environmentof the spill.

As shown in the drawing, top layer 46 may suitably be removed usingconventional skimming equipment 50, and an outlet pipe 52 may suitablybe provided, preferably communicating with a lower portion of separationcompartment 38, for discharging or returning water to the environment.As with compartments 34, 36, separation compartment 38 is preferablycommunicated with flotation compartment 36 by a divider 54 alsopreferably including upper and lower cutouts 42, 44. In this way, theflotation of oil toward top layer 46 is not inhibited by turbulence dueto flow from flotation compartment 36 to separation compartment 38. Oilrecovered through skimming equipment 50 may suitably be transferred to afurther treatment station, or a storage tank or the like.

Still referring to the accompanying FIGURE, the method of the presentinvention will now be further described. In accordance with theinvention, system 10 is preferably transported to the site of a spill,and is positioned with liquid inlet 16 communicating with a spill areaschematically illustrated at 56. A mixture of spilled oil in wateremulsion and environmental water is drawn in through liquid inlet 16 byprimary pump 14, while air is injected into air inlet 18. This mixtureis subjected to shear when drawn through primary pump 14, and additionalair may be injected through air inlet 32, such that the air injectedmixture is sprayed into receiving compartment 34 through line 22,preferably with a velocity sufficient to further enhance the shear towhich the air and liquid mixture is subjected.

Liquid is also preferably drawn from receiving compartment 34 throughoutlet pipes 24 and, with additional air injected through air inlets 30,is passed to additional pumps 26 for application of additional shear,preferably so as to provide an adhesion of oil to air bubbles of atleast about 80% by volume of oil at inlet 16, preferably at least about90% and ideally at least about 98%. This recycled portion of liquid fromreceiving compartment 34 is returned to receiving compartment 34 throughreturn pipe 28.

The air liquid mixture of receiving compartment 34 passes through upperand lower cutout 42, 44 to flotation compartment 36, where oil adheredto air bubbles is allowed to float toward the surface of liquid inflotation compartment 36. The space velocity of liquid and air throughsystem 10 may preferably be set so as to provide a suitable residencetime in flotation compartment 36, typically between about 1 to about11/2 minutes as set forth above, although this time will vary dependingupon the characteristics of the oil or bitumen and water.

In flotation compartment 36, oil adhered to air bubbles at leastpartially separates to the surface. During this time, the at leastpartially separated liquid mixture flows from flotation compartment 36to separation compartment 38 through upper and lower cutouts 42, 44 ofdivider 54, so as to provide liquid in separation compartment 38including top layer 46 of separated oil and the remainder of thecompartment having treated water including less than or equal to about20 parts per million of oil. Conventional skimming equipment 50 ispreferably used to skim off top layer 46 of oil for further treatment orstorage as desired, while outlet pipe 52 can be used to return thesubstantially cleansed water to the environment, preferably at a pointsufficiently spaced from spill area 56 as shown in the drawing.

In accordance with the invention, it has been found that air ispreferably injected to the stream of obtained oil in water emulsion andwater in an amount of between about 6% to about 10% by volume of theincoming stream. This rate of air injection has been found to readilyprovide the desired high percentage of adhesion of oil to air bubbles.

It should be appreciated that although the present disclosure isprovided in terms of injection of air, other suitable gases may be usedwithin the scope of the present invention, if desired, and dependingupon interaction of such gas with the oil and water being treated.

It should also be appreciated that system 10 as described aboveadvantageously operates in an on line manner wherein a stream of spilledemulsion and water are continuously introduced to primary pump 14 whilea steady stream of cleansed water is returned to the environment, andskimmed oil from top layer 46 is transported to suitable containment orstorage facilities.

It should also readily be appreciated that the system and method of thepresent invention provide for the rapid and effective recovery of atleast the oil phase of a spilled oil in water emulsion, thereby reducingthe environmental cost of such spills and recovering the potentiallyvaluable resources which have been spilled.

It is to be understood that the invention is not limited to theillustrations described and shown herein, which are deemed to be merelyillustrative of the best modes of carrying out the invention, and whichare susceptible of modification of form, size, arrangement of parts anddetails of operation. The invention rather is intended to encompass allsuch modifications which are within its spirit and scope as defined bythe claims.

What is claimed is:
 1. A method for on line recovery of oil from an oilin water emulsion spilled in water, comprising the steps of:obtaining astream of recovered material including an oil in water emulsion andwater; introducing a gas into said stream and applying shear so as toprovide a mixture wherein oil from said oil in water emulsion is adheredto bubbles of said gas; passing said mixture to flotation means forallowing said oil adhered to said bubbles to rise to a surface of saidmixture; and removing said oil from said surface of said injectedmixture.
 2. A method according to claim 1, wherein said introducing stepcomprises introducing said stream with said gas in an amount of betweenabout 6% to about 10% by volume of said stream.
 3. A method according toclaim 1, wherein said introducing step comprises introducing said gasand applying said shear so as to adhere at least about 80% by volume ofsaid oil in said stream to said bubbles of gas.
 4. A method according toclaim 1, wherein said introducing step comprises introducing said gasand applying said shear so as to adhere at least about 90% by volume ofsaid oil in said stream to said bubbles of gas.
 5. A method according toclaim 1, wherein said introducing step comprises introducing said gasand applying said shear so as to adhere at least about 98% by volume ofsaid oil in said stream to said bubbles of gas.
 6. A method according toclaim 1, wherein said obtaining step is carried out using a primary pumpmeans and wherein at least a portion of said gas is introduced in saidprimary pump means.
 7. A method according to claim 6, further comprisingpassing said mixture to additional pump means for applying additionalshear and introducing additional gas.
 8. A method according to claim 1,wherein said step of passing said mixture comprises passing said mixtureto a receiving compartment, passing said mixture from said receivingcompartment to a flotation compartment wherein said oil adhered to saidbubbles rises to said surface so as to provide an at least partiallyseparated mixture of said oil adhered to said air bubbles and saidwater, and passing said at least partially separated mixture to askimming compartment wherein said oil forms a layer on top of saidwater;skimming said layer of oil; and returning water from below saidlayer to a surrounding environment.
 9. A method according to claim 8,further comprising the step of dividing at least two compartments ofsaid receiving compartment, said flotation compartment and said skimmingcompartment with a divider wall defining a surface flow zone forcommunication between said at least two compartments and defining abottom flow zone for communication between said at least twocompartments whereby turbulence of flow between said at least twocompartments is inhibited.
 10. A method according to claim 8, furthercomprising the step of recirculating said mixture from said receivingcompartment to means for introducing additional gas and for applyingadditional shear.
 11. A method according to claim 1, wherein said gas isair.
 12. A method according to claim 1, wherein said removing stepprovides a treated water portion having an oil content of less than orequal to about 20 parts per million.
 13. A method according to claim 1,wherein said removing step comprises skimming said oil from said surfaceof said mixture.
 14. A system for on line recovery of oil from an oil inwater emulsion spilled in water, comprising:means for obtaining a streamof recovered material including an oil in water emulsion and water;means for a gas into said stream and for applying shear so as to providea mixture wherein oil from said oil in water emulsion is adhered tobubbles of said gas; and means for allowing said oil adhered to saidbubbles to rise to a surface of said mixture whereby said oil can beremoved from said surface.
 15. A system according to claim 14, whereinsaid means for obtaining comprises pump means having a liquid inlet forobtaining said stream from a site where said oil in water emulsion isspilled in water, and wherein said means for introducing comprises a gasinlet connected to said liquid inlet for injecting said gas into saidstream for shearing in said pump.
 16. A system according to claim 15,further comprising an additional gas inlet for gas downstream of saidpump means.
 17. A system according to claim 14, wherein said means forallowing flotation comprises a receiving compartment for receiving saidstream, a flotation compartment communicated with said receivingcompartment for allowing said oil adhered to said bubbles to rise to asurface of said stream, and a separation compartment communicated withsaid flotation compartment for receiving said stream having a top layerof oil.
 18. A system according to claim 17, further comprisingadditional pump means for shearing said stream, and means forrecirculating said stream from said receiving compartment to saidadditional pump means and back to said receiving compartment.
 19. Asystem according to claim 18, further comprising means for introducingadditional air to said stream upstream of said additional pump means.20. A system according to claim 17, further comprising skimming meansfor skimming said top layer of oil from said separation compartment andoutlet means for discharging water from said separation compartment tosaid site.
 21. A system according to claim 17, further comprisingdividing means positioned between at least two compartments of saidreceiving compartment, said flotation compartment and said separationcompartment and having means defining a surface flow zone forcommunication between said at least two compartments and means defininga bottom flow zone for communication between said at least twocompartments whereby turbulence of flow between said at least twocompartments is inhibited.
 22. A system according to claim 21, whereinsaid means defining said surface flow zone comprises a cutout along atop edge of said dividing means, and wherein said means defining saidbottom flow zone comprises a cutout along a bottom edge of said dividingmeans.